--MAC--
Launch Terminal (Applications / Utilities / Teminal)
Type: sudo nano /private/etc/hosts to open your hosts file
This requires the root password.
Use the arrow keys to move the cursor to the next available line.
Add: 213.133.123.175 www.minecraft.net
Hit Ctrl-X to close the file, then Y to save, then Enter to keep the same file name.
Type: dscacheutil -flushcache
There is no confirmation that this did anything, but you will be on a new line in Terminal.
Start MC and use the password you gave Mejt.
--WINDOWS--
Launch Notepad with administrator permissions (right click on notepad shortcut and run as administrator)
Open c:\windows\system32\drivers\etc\hosts file
Add 213.133.123.175 www.minecraft.net & Save the file.